Effects of different doses of dexmedetomidine pretreatment on cardiac toxicity of bupivacaine in rats / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effects of different doses of dexmedetomidine pretreat-ment on cardiac toxicity of bupivacaine in rats.Methods Forty eight adult male SD rats weighing 250-300 g were randomly divided into 4 groups (n=12)saline control group (group C),dexmedetomi-dine 5 μg/kg group(group D5),dexmedetomidine 10 μg/kg group(group D10)and dexmedetomidine 1 5 μg/kg group(group D1 5 ).A Ⅱ-lead electrocardiogram(ECG)was continuously monitored,the femoral artery was cannulated for direct measurement of MAP and the femoral vein was cannulated for infusion of drugs.Groups D5,D10 and D1 5 were received infusion of dexmedetomidine 5,10 and 1 5μg/kg respectively 1 5 minutes before administration of bupivacaine,while the equal volume of saline was given in group C,then all rats received infusion 0.75% bupivacaine at the rate of 2 mg·kg-1· min-1 until asystole occurred.The doses of bupivacaine and the times of bupivacaine-induced convul-sions,arrhythmia and asystole were recorded respectively,and the myocardial concentration of bupiv-acaine was observed.Results Compared with group C,the doses of bupivacaine and the times of bupivacaine-induced convulsions,arrhythmia and asystole were all increased in groups D5,D10 and D1 5 (P <0.05).Compared with group D5,the above parameters were increased in groups D10 and D1 5 (P <0.05 ).There was no statistical significance of the above parameters between groups D10 and group D1 5.Conclusion Dexmedetomidine pretreatment can raise the threshold toxic dose of bupi-vacaine,delay the time of occurrence of cardiotoxicity of bupivacaine,so that to prevent the cardiac toxicities of bupivacaine in rats,and it produces a dose-dependent protective effect within a certain dose range.